Problem: The arithmetic sequence $(a_i)$ is defined by the formula: $a_1 = 7$ $a_i = a_{i-1} + 3$ What is $a_{2}$, the second term in the sequence?
From the given formula, we can see that the first term of the sequence is $7$ and the common difference is $3$ The second term is simply the first term plus the common difference. Therefore, the second term is equal to $a_2 = a_1 + 3 = 7 + 3 = 10$.